Paging system



Nov. 17, 1942. v. DURBIN ,5

PAGING SYS TEM Filed April 5, 1940 5 Sheets-Sheet l L-J W he Z: FEW

Nov. 17, 1942. w v DURBIN 2,302,535

FAGING SYSTEM Filed April 5, 1940 3 Sheets-Sheet 3 Witness vzvenzar MEFWPatented Nov. 17, 1942 PAGING SYSTEM Vernon Durbin, Newton, Mass,assignor to The Holtzer-Cabot Electric Company,

Roxbury,

Mass, a corporation of Massachusetts Application April 5, 1940, SerialNo. 327,97 5

(Cl. 177-353l 11 Claims.

The present invention relates to paging systems and more particularly tosystems of the general type disclosed in the Lichter Patent 1,780,791and the Baker Patent 1,795,536.

The systems disclosed in the Lichter and Baker patents comprise a seriesof banks of calling keys which, through suitable flasher means, aresequentially connected with annunciator circuits whereby the annunciatorcyclically displays the signals set up on the several banks. Adisadvantage of these systems is that an inactive bank, that is, a bankon which no call is set up, assumes control of its proportionate part ofthe cycle. Thus in a six-bank system, if calls are set up on only twobanks, the annunciator will be dark for at least two-thirds of eachcycle. In my Patent No. 2,052,999 I have illustrated a system in whichthis disadvantage is overcome, the specific embodiment of said inventioninvolving a mechanical flasher which is operated at low speed withrespect to an active bank and at high speed with respect to an inactivebank.

In accordance with the present invention, means are provided.f0r causingthe control of the flasher devices to advance over any bank or banks onwhich no calls are set up, so that the signals set up on active banksare displayed cyclically, and Without the delay periods characteristicof the systems described in the Llchter and Baker patents. The inventionis similar to that of my prior patent, but embodies importantimprovements, particularly in the use of simple and relativelyinexpensive apparatus, in the freedom from moving parts, and in thecertainty and flexibility of the control. In the preferred form of theinvention the control is effected electrically through a series ofsequence relays, each under the control of an activating switch or startswitch. These relays are operated successively only for those banks inwhich the activating means are in active position. Accordingly, signalsmay be set up on any one or several of the banks and the control is suchas to place the annunciator only under the influence thereof, wherebyall active signals are flashed in rapid succession, without any effectby the inactive banks on the annunciator.

Other features of the invention comprise certain novel features ofconstruction and combinations and arrangements of parts arranged for Ithree digits.

diagram of a system in which the signals are given by numbercombinations as in the Baker patent and embodying the features of thepresent invention to avoid delay periods due to inactive banks: Fig. 2is a diagram of the annunciator circuits for the system of Fig. 1; Fig.3 is a simplified diagram with some of the elements rearranged to assistin the explanation of the operation of the system of Fig. 1; and Fig. 4is a simplified diagram of a system to display letter and number signalsof the type described in the Lichter patent and likewise embodying thefeature of avoiding dark periods due to inactive banks.

The invention is illustrated in Figs. 1 to 3 as embodied in a doctorspaging system of a type to give indications similar to those of theconstruction disclosed in the Baker Patent No. 1,795,536. There isprovided a plurality of annunciators 6, each having a number of lamps 8with characteristic symbols illustrated here as numerals 1 to 4. Eachannunciator is also provided with an audible signal device ill.

The system also includes a call board provided with a plurality of banksof call switches, each bank having a switch for each annunclator symbol.In the system herein described three banks of switches are illustratedat I, II and III, and the individual call switches are shown at H. Astart switch or activating switch I2, to be later described in detail,is provided for each bank. The call-board construction may be asdescribed in the Baker Patent 1,963,346, in which the switches afterbeing depressed are held latched in closed position. Each bank also hasa stop key M by which the start switch and any call switches may bereleased. Each bank is also provided with an audible signal switch IS.

The annunciators may comprise any number of lamps with any suitablecharacters, and the buttons for the call switches are provided withcorresponding symbols. In one form, each bank has ten switches numberedfrom 1 to O, and each doctor is assigned a call number consisting of Thecalls for three doctors may be set up on the separate banks of switchesand are displayed in succession on the annunciator. To avoidcomplication of the diagram, the annunciators and banks of call switchesare shown 'as comprising only four characters.

positive terminal of the direct our The call switches are connected inseries with corresponding flasher relay contacts or" the same bank. Theconnections are traced as follows: A bus designated by a plus sign inacircle is connected through leads 22 with the fixed contacts of all thecall switches of the several banks. The movable contact of each switchis connected by a wire 24 with the corresponding flasher contact l6 ofthe same bank. All similar movable contacts ll of the flasher relay areconnected together; thus the movable contacts corresponding to number lare connected to a bus 26 which in turn is connected to a pilot lamp 28on the call board. and also to a power relay 30 which in turn isconnected to the other side of the source, as indicated by a minus signin a circle. Similarly, the other contacts of the several flasher relaysare connected to busses leading to properly numbered pilot lamps and tosimilar power relays. The power relays, when energized, close contactsindicated at 32 connected with annunciator circuits '33 which run to theproper annunciator lamps.

The sources of energy for the annunciator circuits are indicated by plusand minus signs in squares.

The means whereby the flasher relays are energized will now bedescribed: Each relay is connected at one terminal to a bus 34 which isconnected to one side of a source of energy indicated by an unenclosedplus sign. For reasons which will presently become apparent, the flasherrelays and control circuits therefor are energized by direct current,and the source are indicated by unenclosed plus and minus signs. Eitheralternating or direct current may be used for the sources which arerepresented by plus and minus signs in circles and squares. In any casethe signs have no significance as to polarity and simply indicate theterminals of the sources.

The flasher relays are controlled by a chain of three sequence relays S,S and S sequence relays are substantially identical, a description ofone only will suffice. The relay S comprises a winding 36 shunted by aresistor 38 and a condenser 40, and also shunted by a variable resistor42, forming a time constant circuit to determine a period of slowrelease of the relay. The relay has a pair of contacts 44, 48 which openwhen the relay is de-energized and an in dependent set of three contacts48, 59 and 52.

When the relay is tie-energized, contact 50 makes on 52 and when therelay is energized, it breaks contact with 52 and makes on 48. Relays Sand S are identical and corresponding parts are similarly numbered,except that the back contact 52 is omitted from relay S Each startswitch I! comprises a set of three contacts 54, 5B and 58 and a set oftwo contacts and 62. When the switch is up, contact 54 makes on 58, andwhen the switch. is manually depressed, contact 56 makes on 58 and illIre on 62.

There is also provided an impulsing relay or master relay M having twopairs of contacts iii and l0, T2, the former being open the latterclosed when the relay is de-energized.

One side of each winding of the sequence relays and the master relay isconnected to the nt The other side of each sequencerelay cby a wire 14with the contact 58 of its on switch. The upper contact 54 of the 5;start switch is connected by a wire T8 wi '1 the con tact 44 of itscorresponding sequence .y, and exactly similar connections for the otherst t switches and sequence relays are indicated at ni Since the i theannunciators.

and 76". A connection 18 is made from the wire It to the movable contact56 of the second start switch, a connection 18 is made from the wire 16*to the movable contact 56 of the third start switch, a connection I8 ismade from 15 to the winding of the master relay, and a connection 80 ismade from contact 10 of the master relay to the movable contact 55 ofthe first start switch.

To assist in tracing the connections, a simplified diagram is given inFig. 3. The parts are here rearranged by placing each start switch ad;.iacent to its sequence relay and also by changing the arrangement ofthe call switch and flasher relay contacts to shorten the connections.Fig. 3

' is electrically identical to Fig. 1 (except that the call switches arefewer lnnumber) and all connections are similarly numbered, so that Fig.3 may be hereinafter referred to for the description of the sequencerelay operation.

The lowermost fixed contact 62 of each start switch is connected to thenegative terminal of the direct current source. The movable contacts 50of the several switches are connected by wires 84 with a sequence relaycontrol bus 86. The movable contacts 46 of the several sequence relaysare connected by wires 88 to the control bus. The bus is connected atone end to contact 12 of the master relay.

Contact 68 of the master relay is connected to the negative terminal ofthe direct current source, and contact 65 i connected by a wire 90 withthe movable contact 50 of the first sequence relay S. Contact 52 of S isconnected to contact 50 of S by a wire 92, and contact 52 of S isconnected to contact 50 of S by a wire 94.

Contacts 48 of the several sequence relays are connected by wires 96with the terminals of the corresponding flasher relays. The firstflasher relay F is energized whenever its corresponding sequence relayis energized, if the masterrelay is also energized at the same time.This may be seen by tracing a circuit from the positive bus 34 throughflasher relay F to wire 96, con-- tacts 48, 50 of relay S, wire 30 andcontacts 66, 68 of the master relay to the negative terminal of thesource. Flasher relay F is enerl gized when its sequence relay S and themaster relay M are energized, but only under the additional conditionthat the preceding sequence relay S is de-energized, since the circuitfrom F to connection 90 must be traced through contacts 48, 56 of S wire92 and contacts 52, 50 of S. Likewise relay F can be energized only whenrelay S and master relay M are energized and the preceding sequencerelays S and S are deenergized.

A description of the audible signal controls will be deferred until theoperation of the parts thus far described has been explained.

Operation of visible signals When no start switch is depressed, which isthe condition illustrated in the diagrams, all relays are d e-energizedand no indications are given on Assume now that a call is set up on eachbank of call switches and that all three start switches are depressed.For the sake of definiteness, it may be assumed that switch i of bank I,switch 2 of bank II, and. switches l and 2 of bank III are closed,Negative potential is now applied through contacts 62, 60 of any or allof the start switches and through wires 84 to the bus 86. An impulsingcircuit may now be continued through contacts 12, T0 of the masterrelay. wire 80, contacts 55. 58 of the start switch of bank I, andwinding 36 of sequence relay S to the positive terminal of the directcurrent source. This relay is immediately energized, thus closingcontacts 44, 46, At the same time contact 50 closes on 48, which leadsthrough the wire 96 to the flasher relay F, but the flasher relay is notimmediately energized because the circuit is open at contacts 66, 68 ofthe master relay. Closure of contact 46 on 44 applies negative potentialfrom the bus 86 through wire 88 and said contacts to wire l8 which leadsto the movable contact 56 of the start switch of bank II, and an impulseis thus transmitted through 56, 58 to energize relay S Energizaa tion ofS likewise closes its contacts 44, 46, thereby closing an energizingcircuit through wires 18 and contacts 56, 58 of the third start switchto relay S Finally, energization of relay S closes its contacts 44, 46and establishes an energizing circuit through 18 for the winding of themaster relay M. Thus all four relays are energized successively. Thesuccessive energization of these relays occurs very rapidly.

The energization of the master relay opens contacts l0, l2 and thusopens the previously traced circuit through which the relay S wasenergized. The relay, however, does not de-energize immediately becauseof the relatively large time constant aflorded by the shunt'circuits 38,40 and 42. While the contacts of relay S are thus held up, thepreviously described conditions for energization of flasher F aresatisfied, namely, simultaneous energization of relay S and master relayM. This energizing circuit for F may be traced from the negativeterminal of the source through contacts 68. 66 of the master relay, wire90, closed contacts 59, 48 of relay S, wire 96 and winding F" to thepositive bus 34. Relays S S and M are held energized because negativepotential applied to the bus 86 through closed con tacts 60, 62 of theseveral start switches is still fed to the windings of each of theserelays through contacts 46, 44 of the preceding relay and theconnections 18.

Flasher relay F being thus energized, all of its contacts are closed andthe power relay circuits corresponding to closed call-board switches areenergized. Thus, in the example which has been assumed, circuitscorresponding to number 1 are energized and number 1 is displayed on theproper pilot lamp and on all of the annunciators.

After a time determined by the time constant of the winding of relay Sand its shunt circuits,

the relay becomes sufliciently de-energized to' drop its contacts. Thisdisconnects flasher relay F' at contacts 48, 50, whereupon the relay isde-energized and the annunciator indications are extinguished.Furthermore, opening of contacts 44, 46 of relay S opens the holdingcircuit for relay S thereby allowing the latter to deenergize slowlythrough its timing circuit. An energizing circuit for flasher relay F isnow traced from the negative terminal of the source through contacts 68,66 of the master relay, wire 90, contacts 50, 52 of relay S, wire 92,contacts 50, 48 of relay S wire 96 and flasher F to the positive bus 34.Relays S and M remain energized through contacts 44, 46 of the relays Sand S respectively. In the interval of slow deenergization of relay Sthe flasher relay 1? remains energized and thus causes annunciatorsignal numbered 2 to be displayed, this having been set up on the properswitch of bank II.

After relay S has been de-energized sufficiently to drop its contacts,relay S assumes control in exactly similar manner so thatflasher relay Fis energized to display the characters 1 and 2 which have been set up onbank III of the call board. Finally, relay S de-energizes, therebyopening the circuit of flasher F and also opening its contacts 44, 46through which the master relay has been held energized during the wholecycle. The master relay then drops its contacts. As soon as contacts 10,I2 of the master relay are closed, the sequence relays and the masterrelay are again energized in rapid succession, following which therelays de-energize slowly and in succession to control the operations ofthe flasher relays.

It has been found satisfactory to flash at about forty-five times aminute, so that each flash lasts for somewhat over a second The durationof the flashes is determined by the settings of the resistors 42, andthese may be set to give flashes of substantially any desired length.

The operation above described, wherein characters are set up on eachbank, may be considered the normal operation of the system, in that theflasher relays operate successively and give visible indications exactlylike those displayed by the system of the Baker Patent 1,795,536.However, if all three of the start switches are not depressed, thepresent system operates to flash signals from the active banks withoutthe delay period which is characteristic of the system of the Bakerpatent. This may be seen by assuming that a call is set up on bank I andthe start switch for bank I only is depressed. In such a case, relay Sis energized exactly as previously described. However, relays S and Sare not energized. Immediately upon energization of S, a circuit forenergizing the master relay is traced from the negative terminal throughclosed contacts 62, of the first start switch, bus 86, contacts 46, 44of relay S. wire 18, contacts 56, 54 of the second start switch, wire16, wire 18 contacts 56, 54 of the third start switch, wire 16, wire 18and relay winding M to the positive terminal. The energizing impulse maybe therefore considered as advancing past relays S and S Theenergization of the master relay opens the energizing circuit for S,thereby permitting the latter to deenergize slowly, and when thede-energization has progressed sufliciently to drop the contacts, theenergizing circuit from the master relay is again opened. At no time isit possible to energize either of the other cycle relays or to establisha connection to the flasher relays F and F Under such conditions thesequence relay S and the master relay are simply energized anddeenergized successively. The signals set up on bank I are thereforedisplayed almost continuously, except for the short interval of time inwhich the relay S is de-energized. This de-energization of relay 8 givesa flashing signal which is very effective in attracting attention.

From the description thus far, it will be seen that the flasher relaysoperate only for those banks in which the start switches are depressed;thus if a call were set up on bank II or bank'III, the correspondingcycle and flasher relays would be operated, but the cycle and flasherrelays of other banks would be inactive. Likewise, two calls may be setup on two banks and these will be flashed in immediate successionwithout being affected by the inactivity of the third bank. In anyevent, the impulse initiated by closure of master relay contacts 66, 68passes through the operating devices of any active bank or banks andadvances over any inactive bank or banks. In thisembodimtnt of theinvention, an active bank refers to one in which the start switch isdepressed.

It will be noted that a bank for which the start switch is depressedwill control an interval even though no call switch for that bank isclosed. It is thus possible to provide an interval in which no signal isdisplayed but ordinarily the system will not be operated in thatfashion.

The keys may be arranged in any number of banks, with any suitablenumber of keys in each bank. Usually, the banks are three or more innumber, and there are ten keys in each bank numbered from 1 to 0. A callpreferably consists of a three-digit number with the digits in ascendingorder, such as 123, 679, 480, etc, as described in the Baker patent.

Audible signals The manually operated audible signal switches I5, onefor each bank, and the contact groups l8 of the flasher relays havealready been mentioned. The purpose is to give an audible signal, whendesired, during the flash of any visible signal and this feature isordinarily used to indicate an emergency call.

As shown in Fig. 1, each contact group I8 comprises a middle movablecontact and upper and lower fixed contacts. One terminal of each switchI5 is connected to the upper contact of its corresponding group I8 by awire I00. The movable contact of the first group I8, corresponding tobank I, is connected to the positive terminal of the direct currentsource. The lower fixed contact is connected to the movable contact ofthe next group by wire I02, and the lower contact of said group isconnected to the middle contact of the next group by wire I04. The lowercontact of the final group is connected to one terminal of an audiblesignal relay I06, the other terminal of which is connected to "ienegative terminal of the direct current source. The relay I 06 isshunted by a time constant circuit I08 comprising a resistor and acondrnser. When all the flasher relays are de-energized, the audiblesignal relay I06 remains continuously energized, thus holding itscontacts I I closed.

One terminal of each of the audible signal switches I is connected to abus II2, leading through the contacts IIO to an audible signal powerrelay III, which in turn is connected to the negative side of the directcurrent source. The relay H4 is similar to the relays and has contactsfor operating the audible signals I0 through a circuit Hi. It will beseen that when the audible signal switches I5 are left open, the powerrelay I I4 is not energized, regardless of the operations of the flasherrelays.

Assuming now that the audible signal switch I5 for the bank I only isclosed, then when the flasher relay F is energized, under the conditionspreviously described, the movable contact of group I8 of this relayleaves the lower fixed contact and engages the upper contact. Theenergizing circuit for the audible signal relay I I0 is thus opened, butthe relay remains ener ized for a short time because of the timeconstant circuit I08. An energizing circuit for the power relay H4 isnow traced through the middle and upper contacts of group I8, wire E00,closed switch I5 of bank I and bus I I2. The energization of the powerrelay II 4 closes its contacts and operates the audible signals of allannunciators. Shortly thereafter the audible signal relay I00de-energizes through its circuit I08 and drops the contacts II 0. Whenthe flasher relay F is de-energized the audible signal relay I06 picksup again, thus closing its contacts IIO, but no audible signal is givenat that time because the energizing circuit for the power relay isbroken.

The operation of the audible signal controls for the other banks issimilar and need not be described in detail. The audible signal switchesI5 of more than one bank may be closed, in which case an audible signalwill be given upon the activation of each bank for which a switch I5 isclosed.

The audible *nal controls above described are particularly an :nged foruse with audible signal devices of the solenoid type, in which a singlestroke is given upon closure of the main audible signal circuit I56. Ifaudible signal devices of the buzzer type are employed, the relay I06and its contacts may be omitted. An energizing circuit for the powerrelay I I4 would then be traced directly through the contact groups IS,a closed audible signal switch I5, and bus IIZ, whenever the flasherrelay corresponding to such a closed audible signal switch should beenergized. However, some'difiiculty might be encountered if audiblesignal devices of the solenoid type were used with such a simplifiedcircuit. Such signal devices are rather slow acting and might not bede-energized with sufficient rapidity in the relatively short intervalbetween operations of successive flasher relays, in which case theaudibll signal would be lost. This might happen if the audible signalswitches for all active banks were closed. Corr-equently, the circuitabove described is preferably provided. Upon energizetion of any nasherrelay, the audible signal is immediately sounded if the correspondingswitch I5 is closed. The time constant of the relay I05 is long enoughto insure only that the contacts IIO shall remain closed for asuilicient tine to transmit the energizing impulse to the power relay II4, after which the contacts IIO are permitted to open, therebyrestoring the audible signal devices to their original conditior. Thetime constant determined by the circuit I08 may be made considerablyshorter than the time constants for the sequence relays so thatde-energization of the audible signal devices will be assured before theflasher relay of an active bank becomes de-energized.

System 0) Fig. 4

The system illustrated in Fig. 4 is arranged to g 've signals of thetype described in the Lichter Patent 1,780,711. Each annunciator hassignals of two groups, for example, letters A to D and numbers 1 to 16.A call consists of the combination of a letter and a number. By thisarrangement the calling capacity is increased since several numbers maybe displayed with each letter. There are as many banks of calling keysas there are letters and each bank has a key for each number. In theLichter system the letters A, B, C, etc., are displayed automatically insequence, and as each' letter is displayed the numbers set up on thecorresponding bank are displayed therewith. According to the presentinvention. as shown in Fig. 4, the same general results are obtainedexcept that inactive banks are skipped over, that is, no time is takenby banks in which no number keys are set.

The system of Fig. 4 is similar to that of Lgs. 1 to 3, except that somechanges are made to permit activation of a bank by operation of anynumber key therein and without the use of a manual start switch; alsothe number keys are independently releasable to permit cancellation of acall while still allowing other calls set up on the same bank to bedisplayed in their proper sequence.

For simplification, only three banks are shown in Fig. 4, eachcomprising four keys numbered from 1 to 4. Each annunciator I30 has thesignal lamps A, B, C, 1, 2, 3 and 4. Each key has contacts I32,correspondingly numbered contacts of the several banks being connectedthrough appropriate relay circuits with the corresponding annunciatorsignals. Each bank has a start switch I34, electrically identical withthe start switches I2 of the system previously described. but operatedautomatically through a sliding bar I36. The bar is moved to close thestart switch when one or more number keys of the bank are depressed, andis restored to inactive position by a spring I38 when all keys of thebank are released.

The sequence relays, the master relay and the electrical connections tothe start switches are exactly as in Fig. 3, these connections beingomitted from Fig. 4. The flasher relays F, F

and F are also similar to those of Fig. 3, each having a pair ofcontacts in series with correspondingly numbered key contacts of thebank. The flasher relays each have additional contacts I40, connected atone side to the bus and at the other side to circuits (I42, I44, I46)for energizing the respective letter signals. Thus the contacts I40 ofrelay F control energization of the letter A, the similar contacts ofrelay F control energization of letter B, etc. The relay connections tothe annunciators are omitted from Fig. 4. l

Audible signal switches may be provided to operate in the same manner asin the system previously described.

As an example, it may be assumed that doctors Al, A3, CI, C2 and C4 areto be called. Keys 1 and 3 of the first bank and keys 1, 2 and 4 of thethird bank are depressed. The annunciator first displays the letter Atogether with numbers 1 and 3, and then displays the letter C togetherwith numbers 1, 2 and 4, this sequence being repeated at a ratedetermined by the time constants ofthe relay circuits, and without any Bindication. If it is now desired to call a B doctor, say B4, key 4 inthe second bank is depressed, and the annunciator indication B4 entersinto the sequence between the A and C-indications. Any call may becanceled simply by releasing the corresponding key, while stillpermitting other calls set up on the same bank to be displayed; thus ifkey 1 of the A bank is released, the call A3 will continue to bedisplayed in its proper sequence. When all keys of a previously activebank-are released, the start switch for that bank is opened, and thebank no longer has any control over the system. If one bank only isactive, its letter and number indications will be displayed practicallycontinuously, except for the short flashing intervals caused by thetiming operations of the relays.

As in the first system described, the system may be extended to anynumber of banks, with any number of keys in each bank.

Having thus described the invention, 1 claim:

1. A sequence control system comprising a plurality of sequence relayshaving individual output means associated therewith and controlledthereby, manual activating means for each sequence relay, an impulsedevice, means operated by any of said activating means for actuating theimpulse device, means operated by an impulse generated by the impulsedevice for energizing in succession only those sequence relays for whichthe manual activating means have been operated, a timing circuit foreach sequence relay to determine a period of slow de-energizationthereof during which its output means is operative, connections to causeslow sequential de-energization of the relays which have been previouslyenergized in a cycle of variable length depending on the number of suchactivated relays, and means controlled by the last of said relays tooperate the impulse device to initiate a new cycle, whereby saidselected relays are separately and sequentially in control of theiroutput means in substantially continuous succession.

2. A sequence control system comprising a plurality of sequence relayshaving individual output means associated therewith and controlledthereby, manual activating means for each sequence relay, an impulsedevice, means operated by any of said activating means for actuating theimpulse device, means operated by an impulse generated by the impulsedevice for energizing in succession only those sequence relays for whichthe manual activating means have been operated, a timing circuit' foreach sequence relay to determine a period of slow de-energizationthereof during which its output means is operative, connectionscontrolled upon completion of deenergization of a relay to initiatede-energization of the next succeeding energized relay, and meanscontrolled by the last of said activated relays to operate the Impulsedevice to initiate a new cycle of operation, whereby said selectedrelays are separately and sequentially in control 01' their output meansin substantially continuous succession.

3. A sequence control system comprising a. plurality of sequence relayseach having a timing circuit to determine a period of slowde-energization thereof during which each relay is in control ofindividual output means associated therewith,

: a start switch for each relay, an impulse relay,

means operated by the impulse'relay to establish energizing circuits foronly those sequence relays for which the corresponding start switchesare closed, the energizing circuit for each such sequence relaysubsequent to the first being established through contacts of thepreceding relay which is energized, connections operated by energizationof the last of said relays to open the energizing circuit of the firstof said relays and thus to cause sequential de-energization of theenergized relays at intervals determined by the timing circuits thereof,whereby the individual output means associated with the selectedsequence relays are rendered separately operable in substantiallycontinuous succession.

4. A sequence control system comprising a chain of sequence deviceshaving individual output means associated therewith and controlledthereby, a manually operated activating device for each sequence device,an impulse device to initiate cycles of operation of the sequencedevices, means for operating in a definite cycle only those sequencedevices for which the activating devices have been set in operativeposition, timing means to determine timed operation of the individualsequence devices during which each device is in control of itsassociated output means to cause separate and successive operation ofsaid devices in a cycle of variable length depending on the number ofsequence devices in operation, and means controlled by the last of theactivated sequence devices in the chain to operate the impulse device toinitiate a subsequent cycle of operation.

5. A sequence control system comprising a chain of sequence relayshaving individual output means associated therewith and controlledthereby, a manually operated activating device for each sequence relay,an impulse device to initiate cycles of operation of the sequencerelays, means for operating in a definite cycle only those sequencerelays for which the activating devices have been set in operativeposition, timing means to determine timed operation of the individualsequence relays during which each relay is in control of its outputmeans to cause separate and successive operation of said output means ina cycle of variable length depending on the number of sequence relays inoperation, and means controlled by the last of the activated sequencerelays in the chain to operate the impulse device to initiate asubsequent cycle of operation.

6. A sequence control system comprising a chain of sequence devices,activating means for each sequence device effective to control operationthereof, an impulse device having connections through said activatingmeans to only the sequence devices for which the activating means are ineffective position to abnormalize said sequence devices, means forimmediately thereafter normalizing said sequence devices sequentiallyincluding timing means for determining definite times of normalizationfor said devices, individual output circuits associated with thesequence devices, each operable only during the interval ofnormalization of the corresponding sequence device, and means controlledby normalization of the last activated sequence device to operate theimpulse device to cause a repetition of the cycle, whereby said selectedsequence devices and associated output means are separately operated insubstantially continuous succession.

7. A sequence control system comprising a chain of sequence relays, amanually operated activating device for each relay, an impulse device toenergize the first sequence relay for which the activating device hasbeen set, connections for rapidly energizing successive activatedsequence relays, said connections for each sequence relay operating fromthe preceding sequence relay which is energized, means for slowlyde-energizing the sequence relays successively, individual output meansassociated with the sequence relays and each operable during theinterval of de-ener- ,gization of the corresponding sequence relay, and

means controlled by'de-energization o! the last sequence relay foroperating the impulse device to initiate a new cycle of said operations,whereby the selected sequence relays and their associated output meansare separately operated in substantially continuous succession.

8. A sequence control system comprising a chain of sequence relays,activating means for each sequence relay effective to control operationthereof, an impulse device having connections through said activatingmeans to only the sequence relays for which the activating means are ineffective position to abnormalize said sequence relays, means forimmediately thereafter normalizing said abnormalized sequence relayssequentially including timing means for determining definite times ofnormalization for said relays,

individual output circuits operable during the intervals ofnormalization of the corresponding sequence relays, and means controlledby normalization of the last activated sequence relay to operate theimpulse device to cause a repetition of the cycle, whereby the selectedsequence relays and associated output circuits are rendered separatelyoperable in substantially continuous succession.

9. A sequence control system comprising a chain of sequence relays, amaster relay, a main energizing circuit from contacts of the masterrelay to the first of the sequence relays, energizing circuits fromcontacts of each sequence relay to the relay next succeeding and fromcontacts of last sequence relay to the master relay, manual switch meansfor each sequence relay to render the energizing circuit therefor eithereffective or ineiiective, a de-energizing circuit for each relayincluding timing means to determine a time of slow de-energizationthereof, means for sequentially establishing the de-energizing circuitsfor the energized relays only, and individual output circuits operatedin the intervals of slow deenergization of the corresponding sequencerelays.

10. A sequence control system comprising a chain of sequence relays, amaster relay, 8. main energizing circuit from contacts of the masterrelay to the first of the sequence relays, energizing circuits fromcontacts of each sequence relay to the relay next succeeeding and fromcontacts of last sequence relay to the master relay, manual switch meansfor each sequence relay having, when in active position, a contact toconnect the relay with its energizing circuit and, when in inactiveposition, another contact connected with the energizing circuit of thesucceeding relay, the master relay having contacts to open the mainenergizing circuit when the master relay is energized, a timing circuitfor each relay to determine a time of slow de-energization thereof,contacts closed when the master relay is energized to effect sequentialde-energization of the energized relays under control of their timingcircuits, and individual output circuits operated in the intervals ofslow de-energization of the corresponding sequence relays.

11. A sequence control system comprising a chain of sequence relays eachin control of an output circuit, individual timing means associated witheach relay for determining the duration of the period such relay, uponbeing rendered operative, is in control of its output circuit, manullyoperated devices in control of each relay for selecting the relays to beoperated in sequence, means for operating one after another of theselected relays to cause each to be successively ln timed control of itsoutput circuit, said means including. connections which, upon thecompletion of the control period of one relay, cause the immediateinitiation of the control period of the next selected relay, wherebyonly one relay and its output circuit is operative at a time and thelength of a cycle of operations is substantially the sum of the separatecontrol periods of the selected relays, and means operative uponcompletion of a cycle of operation of any length to render operativeagain the first selected relay of the sequence and thereby immediatelyinitiate a new cycle of operation of selected relays.

VERNON DURBIN.

